Conventionally, as a method for injecting fuel into an internal combustion engine, there is known a method which predicts an amount of fuel to be supplied into a combustion chamber, supplies the predicted amount of the fuel to a combustion chamber, thereafter re-predicts an amount of fuel to be supplied into the combustion chamber prior to the closing of an intake valve for determining a shortage amount of fuel, and re-supplies the determined shortage amount into the combustion chamber (e.g. refer to Japanese Patent Laid-Open No. 1-285640). According to this method, the amount of the fuel to be supplied into the combustion chamber is predicted using an intake pipe pressure and an engine rotational speed calculated from various kinds of parameters.
As in the case of the aforementioned conventional example, however, even if the intake pipe pressure and the engine rotational speed calculated from various kinds of parameters are used, it is difficult to accurately predict the amount of fuel to be supplied into the combustion chamber. For this reason, the method according to the conventional example has a disadvantage in that an air-fuel ratio of the mixture in the combustion chamber may deviate from a target value thereof.
To this end, an object of the present invention is to provide a device and method for controlling an internal combustion engine, which is capable of accurately obtaining an amount of required fuel and suitably approximating an air-fuel ratio in a combustion chamber toward a target value.